Platinum-based drugs are among the most active and widely used anticancer agents and cisplatin represents one of three FDA-approved, platinum-based cancer chemotherapeutics. Although cisplatin is effective against a number of solid tumors, especially testicular and ovarian cancer, its clinical use has been limited because of its toxic effects as well as the intrinsic and acquired resistance of some tumors to this drug. To overcome these limitations, platinum analogs with lower toxicity and greater activity in cisplatin-resistant tumors have been developed and tested, resulting in the approval of carboplatin and oxaliplatin in the United States. Carboplatin is generally less nephrotoxic, and oxaliplatin exhibits a different anticancer spectrum from that of cisplatin. Oxaliplatin has been approved as the first or second line therapy in combination with 5-fluorouracil/leucovorin for advanced colorectal cancer, for which cisplatin and carboplatin are essentially inactive. These platinum drugs have platinum in the 2+oxidative state (Pt(II)).
Novel developments in nanomedicine are directed towards improving the pharmaceutical properties of the drugs and enhancing the targeted delivery in a cell-specific manner. Several cell-specific drugs are known in literature, and include monoclonal antibodies, aptamers, peptides, and small molecules. Despite some of the potential advantages of these drugs, disadvantages have limited their clinical application. Such disadvantages include size, stability, manufacturing cost, immunogenicity, poor pharmacokinetics and other factors.
However, nanoparticulate drug delivery systems are attractive for systemic drug delivery because of their ability to prolong drug circulation half-life, reduce non-specific uptake, and better accumulate at the tumors through an enhanced permeation and retention (EPR) effect. As a result, several therapeutic nanoparticles, such as Doxil® and Abraxane®, are used as the frontline therapies. Nevertheless, research efforts have heretofore focused on single or multiple drug encapsulations or tethering without cell-specific targeting moieties. The development of nanotechnologies for effective delivery of drugs or drug candidates to specific diseased cells and tissues, e.g., to cancer cells, in specific organs or tissues, in a tempospatially regulated manner can potentially overcome the therapeutic challenges faced to date.